Question

A theme throughout our course has been Phenotype because Protein. As we consider these examples we need to understand what the phenotype/product is, how a protein is responsible for it and what specifically is the protein targeted with the technology. So, what is the molecular product of golden rice? What is the protein targeted for this technology? 7-10 sentences.

Answer 1

Golden rice is formed by the engineering of japonica variety of rice . The endosperm of Golden Rice (Oryza sativa) is yellow due to the accumulation of β-carotene (a precursor of vitamin A ) and xanthophylls produced through genetic engineering ,in the edible parts of rice. Golden rice differes from its parent strain due to the addition of some beta carotene synthesizing genes.

The genes introduced to the rice are :

1. psy (phytoene synthase) from daffodil

2. crtI (phytoene desaturase) from the soil bacterium Erwinia uredovora

Although genes code for proteins, β-carotene is produced by a series of biochemical reactions, catalysed by specific enzymes. Each of these enzymes (which are proteins) are coded by genes. The enzymes involved in this pathway are phytoene synthase, phytoene desaturase, carotene desaturase and lycopene beta saturase. In the genetic engineering process of Golden rice, The psy and crtI genes are inserted into the rice nuclear genome. an endosperm-specific promoter controls and limits its expression only in the endosperm.The end product of this engineered pathway is lycopene . Lycopene is further processed to beta-carotene in the endosperm, giving the rice the distinctive yellow color (the phenotype) for which it is named.

Thankyou

Himashree Sarma